Investigation on impact and DWTT resistance at low temperatures in Nb and Ti micro alloy steels

Depending on the climatic conditions in which they are used, new generation petroleum pipe steels come up with the need for high strength and excellent toughness. During the transportation of oil and natural gas, these steels should be at the highest level of impact resistance along with high hardness. In recent years, the general test temperatures, such as 0oC, tend to be lower minus degrees. In this study; (American Petroleum Institute X70 Quality) API X70, impact, (drop -weight tear test) DWTT, and strength were modeled on rolls with thicker than 10 mm. In addition, the necessary parameters for high impact strength at low temperatures were determined by modeling. After the steel production and rolling with the specified parameters, mechanical tests and microstructure examinations were carried out. In order to determine the effect of strength and toughness on mechanical properties, different test sets were prepared for chemical analysis and rolling parameters. The differences in the product microstructure and test results of the titanium level and different holding times and thermomechanical and conventional rolling were investigated. The impact energy values of the materials produced with different process parameters were examined using large data sets. As a result, it has been determined that the particles produced by the thermomechanical rolling method and the particles are the most minor and homogeneously dispersed in the microstructure meet the expectations in terms of material quality.